Hardfacing is a metalworking process where harder or tougher material is applied to a base metal, typically by an arc welding process. One common technique for achieving hardfacing is to form a weld puddle on an area to be hardfaced and concurrently feed a particulate with favorable wear and/or abrasive characteristics into the weld puddle, effectively creating a surface composite upon solidification.
Some current robotics-based hardfacing systems employ a workpiece fixed in a given location, with a movable arc welding unit and a concurrently-operating feed system for the particulate (e.g., tungsten carbide) being used together to achieve the desired hardfacing. Such a feed system generally incorporates a stationary bin/source of the carbide, a vibratory flow metering device fixed below the bin/source, a feed-out mechanism, and a delivery hose interconnecting the vibratory flow metering device and the feed-out mechanism. The stationary bin and the associated vibratory flow metering device are often fixed in a position several feet above the welding zone in order, in part, to create a sufficient flow of carbide through the delivery hose (i.e., provide a sufficiently steep flow angle to ensure movement of the carbide through the delivery hose) and to keep the welding area reasonably clear of obstructions to maximize the working space. The feed-out mechanism, on the other hand, mimics the travel of the movable arc welding unit so that the particulate being delivered via the feed-out mechanism can be delivered into the molten zone of the arc welding puddle created by the arc welding unit. That sort of travel is usually ensured by affixing the feed-out mechanism to the arc welding unit.
A schematic of a prior art version of such a vibratory carbide hardfacing system 510 (one variant of which is available through Rankin Carbide Automation (Rancho Cucamonga, Calif.)) and is illustrated in FIG. 1 That system 510 includes a vibratory feeder assembly 535, a built-in carbide hopper or bin 532, delivery or drop hose 567, a metering funnel 564, a metering tube 514, and a welding gun 512. A particle feed system 516, swing arm 571, tabletop 580, carbide catch tray 582 and controller 585 are also shown The vibratory feeder assembly 510 is set to oscillate, for example at 70-85 cps (cycles per second) to promote delivery of the carbide to the weld pool. The weld gun 512, when used as part of an automatic process, is able to oscillate at a rate of about 1-5 Hz with an amplitude of about 1-9 mm, creating beads about ⅝ inch-1 inch wide (max 1.5 inches wide). The system is designed to aim the carbide into the trailing side of the arc puddle.
Since the feed-out mechanism in the form of the metering tube 514 is moving and the bin 532 is stationary, that combination results in the delivery hose 567 being fixed at one end and moving quite rapidly at the other, as part of a mass-production hardfacing production process. The delivery or drop hose may be on the order of five feet in length while the metering tube may be on the order of four-inches in length. These dynamics associated with the motion of the delivery hose 567 and the overall length thereof creates a number of challenges. First, harmonics in the delivery tube cause a sloshing effect therein that can cause the delivery tube 514 to wear out fairly quickly. Secondly, the same harmonics/motion makes it much more difficult to control the placement of the carbide/abrasive within the weld puddle and, likewise, to achieve even distribution of the abrasive throughout the finished weld bead. Furthermore, a drop length of at least 4-5 ft. is typically used in order to ensure adequate flow through the delivery hose 567 over the full range of motion of feed-out mechanism (i.e., the angle of the delivery tube 514 must be close enough to vertical to avoid clogging). Because of that large drop length and the density of the carbide particulate, the speed and momentum gained by the carbide/particulate upon impact of the weld puddle can be significant, which can promote carbide and/or weld metal splash, neither of which would promote a good, uniform hardfacing. Finally, because of the difficulty in controlling the placement of the abrasive in the desired location, an undesirable amount of the abrasive can end up on floor and/or otherwise going to waste. Accordingly, the desire is to provide a system that can overcome one or more of those challenges.